Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the sensitivity Se as a percentage. Round to one decimal place.
Evidence-based practice statistics worksheet with answers
Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the negative predictive value NPV as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A case-control study compares 60 patients with a disease (cases) and 390 people without it (controls). The table shows how many in each group were exposed to a risk factor. Find the odds ratio OR for the exposure. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 100 patients received a new treatment and 480 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the number needed to treat NNT to prevent one event. Round up to a whole number of patients.
Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 14% in relative terms (RRR = 14%). In a patient group the risk without treatment (CER) is 14% over five years. Find the number needed to treat NNT for five years to prevent one event. Round up to a whole number of patients.
Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 48% in relative terms (RRR = 48%). In a patient group the risk without treatment (CER) is 3% over five years. Find the number needed to treat NNT for five years to prevent one event. Round up to a whole number of patients.
Answer key
- 1. Se = 96.3 %
- 2. NPV = 98.3 %
- 3. OR = 4.17
- 4. NNT = 17
- 5. NNT = 52
- 6. NNT = 70
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